Radio apparatus



July 10, 1934. I H, J, Lows 1,965,660

RADIO APPARATUS Filed Nov. 3, 1930 gwntoc Hume/2 Jim/Z15.

w/fl M 117% WW Patented July 10, 1934 UNITED STATES PATENT OFFICE assignments, to Radio Corporation of America, New York, N. Y., a corporation of Delaware Application November 3, 1930, Serial No. 492,917

2 Claims.

This invention relates to an antenna circuit and in more particular to an antenna circuit for a remotely located radio receiver or the like.

, In the installation of a radio receiver in apart- 5 ment houses, sky-scrapers etc. it becomes necessary to have a very long lead-in that is a source of disturbance in the conventional antenna circuits, in that the long lead-in picks up local disturbing signals that are of such a magnitude that l their energy level is substantially equal to or even greater than that of the desired incoming signal.

An object of this invention is to reduce the undesirable disturbances usually local in source that are picked up by long lead-ins. This has been il-accomplished by providing a step-down transformer near the aerial or the receiving portion of the antenna having the primary connected between the aerial and ground and the secondary to a transmission line that is connected to the QQ- primary of a step-up transformer that has the secondary winding connected to the input terminals of the radio. This second transformer is located near the radio receiver so that undesirable sdisturbances picked up by one side of the transmission line is substantially neutralized by the disturbances picked up by the other side of the transmission line.

In the present modification the volume enclosed by the antenna is comparatively small in that the receiving portion or the aerial of the antenna is placed near the counterpoise which may be the roof of the building or a conductor supported in proper relation with respect to the aerial or the like. The transmission line transferring the signal from the aerial to the radio receiver encloses a very small loop or volume in that the transmission line may be made from a pair of twisted conductors.

Further objects and advantages of the present 4 invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawing:

In the single figure a schematic diagram of the antenna circuit has been shown.

In the drawing the reference character 10 indicates the receiving portion or the aerial of an antenna mounted on top of a tall building or any other suitable place. It has one terminal 11 connected to the primary 12 of a step-down transformer 14. The primary of the transformer 14 I has the other terminal 16 connected to the roof T or any other suitable counterpoise hereafter (Cl. 250-33) i called ground near the aerial 10 so that the loop formed by the aerial and the counterpoise or ground is very small. It can be readily seen that in large cities where there are numerous sources of disturbing signals, it is desirable to mount the so aerial 10 as far from the earths surface as possible for the reason that disturbing signals diminish rapidly as the distance from the source increases.

A pair of transmission lines 18 and 20 connect the secondary 22 of the step-down transformer 5 14 to the primary 24 of a step-up transformer 26 having the secondary 28 connected to the antenna posts 30 and the ground post 32 of a radio receiver not disclosed. Both the primary and secondary windings of the step-down and stepup transformers have their terminals grounded. In the single figure these terminals have been grounded at both ends of the transmission line. For certain installations it may be desirable to have them groundedat only one of the ends. It has been found that a transmission line several hundred feet in length gives very good results when made according to this invention. Such a transmission line tends to neutralize the signals picked up by one line with the signals picked up by the other thereby reducing undesirable disturbances.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all comingwithin the scope of the claims which follow.

What is claimed is as follows:

1. A radio energy interceptor arrangement for remotely located radio receiving apparatus and the like comprising in combination, an aerial for receiving signal impulses, a counterpoise for said aerial and displaced therefrom only a comparatively short distance so that the path for transferring the charges of electrical energy between the aerial and counterpoise is comparatively short, a step-down radio frequency transformer having its primary circuit in series with the aerial and counterpoise, a transmission line comprising a pair of twisted conductors, a step-up transformer having its primary winding connected to the secondary winding of the step-down transformer through said transmission line and the secondary winding of said step-up transformer having its terminals connected to the input terminals of the radio receiver so that the voltage of the signal impulse is reduced while being transmitted over the transmission line and increased when transferred to the radio receiver, said transmission line picking up equal disturbing voltage impulses that closely associated wires, in which one of said wires is grounded, a step-up transformer having its secondary winding connected to the input terminals of a radio receiver, said transmission line connecting the secondary winding of the stepdown transformer to the primary winding of the step-up transformer whereby signal impulses picked up by the receiving portion of the antenna are transmitted to the receiver and whereby the voltage impulses picked up by one side of the transmission line are substantially neutralized by the impulses picked up by the other side of the transmission line.

HOMER J. LOFIIS. 

